Intensity Minutes not showing on dashboard.

Rich said:

Does anyone know why this is?

Yes, the HR Zone alone is not that important (at least on many Garmin models). What is more important (unless your watch allows the direct assignement of the HR Zone to the IM level), is the ratio between your current HR, and the average Resting HR for given day. So if you do not wear the watch during the sleep or rest, then it will be difficult to reach the required ratio of HR/RHR.

And then, in order to earn intensity minutes credit, you must reach or exceed 10 consecutive minutes where your heart rate is elevated above the threshold that is considered moderate intensity. Intervals with HR above the limit shorter than 10 minutes will not be counted.

More info: How can I earn intensity minutes credit? 

Thanks for the info Trux, really useful. So does that mean that if, for example, I do 9 minutes in Z3, then 9 mins in Z4, then 9 minutes in Z3, none of those minutes will register, yet if I do just 11 mins in Z3, it will register?

That sounds a bit bonkers, as the first example has clearly been more intense. ;o)

Rich said:

I do 9 minutes in Z3, then 9 mins in Z4, then 9 minutes in Z3, none of those minutes will register, yet if I do just 11 mins in Z3, it will register?

If there is no drop between the individual 9 minutes intervals, then 27+9 IMs will be counted. Only if the HR drops below the threshold, in the time between the intervals shorter than 10 mins, they won't be counted.

Ahhh, right. What you say ties in with the heart rate graph. There were 3 occasions where the HR just about dropped back into Z2, so there were was no continuous 10 minute period above Z2.

I had read about the continuous 10 minute thing, but I'd assumed from the actual exercise that I wouldn't have dropped into Z2 so many times, however the graph confirmed I had. Maybe I'm getting fitter!!

Thanks again, very helpful.

Now I'm back to being a bit confused. Just been out for a very leisurely walk with the family. I registered 25 minutes in Z1 and 7 minutes in Z2, didn't even start breathing heavily.

That leisurely walk added 32 minutes to the intensity dashboard, yet this morning's activity where I spent 18 minutes in Z3 and Z4, and was breathing heavily for most of it, registered nothing on the dashboard.

That just doesn't seem right.

... another possibility is that your Resting HR was rather high in the morning (did you wear the device in the preceding night?), while you perhaps kept it on during the rest before you did your walk, hence both activites used different RHR. As I wrote, most Garmin devices base the calculation on the HR/RHR ratio, and not on the HR Zones.

I only wear the device (Forerunner 35) during exercise, I don't wear it all the time, so I don't have a daily HR graph. Really appreciate your help with this.

Here are the HR details from the activity that didn't register any intense activity....

Here are the details from the leisurely walk activity that registered 32 minutes of activity...

Righty oh, I'll give that a go. Thanks ;o)